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Antioxidative parameters of fruit model product.
KRATOCHVÍLOVÁ, Lenka
The content of the main components (anthocyanins, quercetin, chlorogenic acid, L-ascorbic acid, rutin, total polyphenols) was determined in the syrup of elderberries (Sambucus nigra L.) by spectrophotometry or high-performanceliquid chromatography. Furthermore, the antioxidant activity of this syrup was determined using three methods: ABTS, FRAP, and DPPH. The measurement results were statistically processed and compared using correlation analysis, specifically using the Pearson correlation coefficient. It was found that the prepared product contains 2160 mg/kg anthocyanins, 201 mg/kg rutin, 26 mg/kg chlorogenic acid and 679 mg/l polyphenols. No free quercetin was found. The content of L-ascorbic acid in the original elderberries was relatively low and therefore for study purposes, the syrup was enriched with this substance in the amount of 0.5% (w/w) to study the connection of its content with other substances. It is clear from the statistical processing that the concentration of chlorogenic acid correlates with the antioxidant activity measured by the FRAP method and the concentration of polyphenols to the antioxidant activity measured by the DPPH method.
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Preparation of rolls with addition of alternative flours
UHLÍŘOVÁ, Lenka
This bachelor thesis is focused on the production of ordinary pastry with the use of alternative flour. Four kinds of crop flour, made from seed pomace of flax (Linum usitatissimum L.), hemp (Cannabis sativa L.), squash (Cucurbita pepo L.) and milk thistle (Silybum marianum L.), were selected. In the literary part of the thesis, common pastry according to legislation, basic and auxiliary raw materials for production and production technology are all de-fined. The crops, from which the addition to wheat flour was processed, are also described. The practical part deals with the production of five types of wheat buns. Four of them are enriched with 5 % of flour made from seed pomace of the four mentioned crops. Production of buns was followed by sensory evaluation according to the descriptors. Weight lost by baking, the quantity of polyphenolic substances and antioxidant activity were also evaluated.
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Evaluation of beetroot qualitative parameters
MIKEŠOVÁ, Mariana
The thesis si lead to evaluate volume of betalain pigments and analyze antio-xidant activity in selected species of beetroot. The thesis is sorted to several chapters . The first chapter discusses about history, individual species of beetroot and general properties. There are information about antioxidant activity and pigments, which is occure in beetroot in the next. The second part of the thesis is focused on analyze the betalain pigments and evaluate antioxidant activity. It leads to resume, that beetroots with red-violet color are more rich about antioxidant substances. Examination of the individual colours for the selected varieties revealed that the 'Redshine' varieties were mainly rich in beta-cyans and betaxantines. "Monorubra." The highest content of these dyes are the varieties which have the colour of the pulp red to dofia-lova. Their values were significantly higher than those of the 'Boldor F1' variety, which would have been expected to have a higher betaxantine content than the red-coloured varieties
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Production of enzyme hydrolysates from flaxseed proteins and evaluation of their properties
HAŠKOVÁ, Kateřina
This thesis focuses on effect on antioxidant properties and chosen functional properties: solubility, water and fat holding capacity, emulsification activity and stability caused by hydrolysis of protein isolates (PI) made from three different flax varieties (Libra, Agriol and Raciol). Part of this work was production of PI from flax seed. For hydrolysis trypsin, alcalase and papain were used - hydrolysis by trypsin was the mildest, while hydrolysis by papain was the most intensive one. Dynamics and degree of hydrolysis were also observed. Solubility of PI and hydrolysates was discovered to be very high (almost 100%). On the contrary water holding capacity was lower (3,93 g/g and less) than fat holding capacity (4,34 g/g), which increased upon hydrolysis for most enzymes, while water holding capacity decreased. Emulsification activity rised (1,47×) under the effect of hydrolysis, however stability dropped (1,3×). The best emulsifiction properties were found out in trypsin hydrolysates. Hydrolysis caused great impact on content of polyphenols which were in alcalase hydrolysates up to 3× higher and on antioxidant activity which grew in papain hydrolysates up to 2,5×.
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Evaluation of cultivar effect on content of betalain pigments in beetroot
AUEROVÁ, Anežka
The thesis si lead to evaluate volume of betalain dyes and analyze antioxidant activity in selected species of beetroot. The thesis is sorted to several chapters . The first chapter discusses about history, individual species of beetroot and general properties. There are information about antioxidant activity and dyes, which is occure in beetroot in the next. The second part of the thesis is focused on analyze the betalain dyes and evaluate antioxidant activity. It leads to resume, that beetroots with red-violet color are more rich about antioxidant substances. It is more healthier than others.
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The content of antioxidants in raw materials and their stability in enriched foods depending on the processing technology
BEDRNÍČEK, Jan
Oxidation reactions, that can negatively affect safety and sensory properties, take place during food storage. To inhibit such an unwanted process, natural polyphenolic antioxidants can be added to food. The aim of this thesis was to study the effects of the addition of polyphenol rich plant materials on chemical and sensory properties of commonly consumed food products. Two types of polyphenol rich plant material were chosen: onion (Allium cepa L.) peel, which is processing by-product and rosemary (Rosmarinus officinalis L.) extract Inolens 4. The addition of polyphenol rich material (both, onion peel and rosemary extract) increased antioxidant activity of food and also delayed lipid oxidation in meat products. Unfortunately, in some cases the addition caused deterioration of sensory properties leading to poor consumers' acceptance. This was observed mainly after the addtition of onion peel powder in higher amounts. The addtition negatively affected hardness of texture. On the other hand, onion peel powder can effectively cover or reduce formation of unpleasant fishy odour, that is typical for fish products stored for long period of time. Additionally, several coumpounds occurring only in onion peel were identified (4 types of quercetin dimer and 1 type of trimer) and their stability during thermal treatment of fortified food was elucidated. This was first study that described this phenomenon. Overall, it can be concluded that plant polyphenols have the potential to extend shelf life of food products.
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Isolation and characterization of beta-glucans of natural origin
Ratsilouskaya, Lizaveta ; Hoová, Julie (referee) ; Márová, Ivana (advisor)
The bachelor thesis deals with the characterization of natural beta-glucans and other active substances isolated from macroalgae and yeasts. The used macroalgae samples differ in the pigment, origin and method of algae processing. The theoretical part focuses on seaweed and yeast species, beta-glucans, their sources and biological effects, other biologically active substances (such as polyphenols and antioxidants) and finally on methods for determining these biologically active substances. In the practical part, samples of selected macroalgae were analyzed, namely samples of Arame, Nori, Kombu, Wakame, Hijiki and Spaghetti. Aqueous, ethanol and acetone extracts of these algae were prepared in this work. The aqueous extracts were used for spectrophotometric determination of phenolic substances, flavonoids and antioxidant activity by the ABTS method. Furthermore, ethanol and acetone extracts of said macroalgae were used to determine total chlorophyll and carotenoid content spectrophotometric. The work also focused on beta-glucan content, analyzing macroalgae and yeast R. toruloides. Arame and Nori algae and R. toruloides were high in beta-glucans. However, beta-glucans were very low in other macroalgae.
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